In order to improve the surface quality of stainless steel pipes, that is, to reduce the energy level and reduce the number of interlayers by improving the surface morphology and morphological structure, we make stainless steel pipes that meet customer requirements. The most common surface treatment methods are as follows: AP/CP: Pickling or passivation (Pickled & Passivated/Chemically Polished) The pipes are pickled or passivated, which will not increase the surface roughness, but will remove the remaining particles on the surface and reduce the energy level, but will not reduce the number of interlayers. AP is pickling treatment, which uses acidic solutions such as nitric acid and fluorinous acid to remove the oxide layer of steel pipes. Cheap and fast, but it is easy to cause grain boundary corrosion and the inner and outer surfaces are rough and easy to have suspended impurities attached. MP: Mechanical polishing is commonly used for oxide layers, holes and scratches on the surface of steel pipes. The brightness and effect depend on the type of processing. Also after mechanical polishing. Although it is more beautiful, it will also reduce the corrosion resistance, so it needs to be passivated when used in a corrosive environment. Moreover,...
The basic design idea when preparing nano-silver on the surface of stainless steel is to make nano-silver exist stably, uniformly and for a long time. Due to the poor binding force between nano-silver and stainless steel, it is difficult to exist stably on the surface of stainless steel alone. On the surface of stainless steel, according to previous studies, the carrier is usually holes, inorganic coatings, etc., combined with the preparation method of nano-silver and the preparation method of antibacterial stainless steel, it is found that electrochemical method and sol-gel method can be used to load nano-silver on the surface of stainless steel. (1) Electrodeposition method The traditional electrodeposition method to prepare nano-silver is to directly deposit silver on the cathode, and then peel off the metal powder of the cathode. The prepared powder has the advantages of high purity, large specific surface area, controllable powder particle size, and automatic production. Widely used in the preparation of nano-silver powder. However, this method can only be used to prepare powder, and cannot directly and stably prepare nano-silver on the surface of stainless steel. The nano-silver preparation method selected in this paper is to use pulse electrodeposition technology to prepare nano-scale silver...
How to deal with the problem of uneven wall thickness of precision seamless steel pipes in the production process? The uneven wall thickness of the steel pipe is mainly reflected in the uneven wall thickness of the spiral, the uneven wall thickness of the linear wall, and the uneven wall thickness of the head and tail. The influence of continuous rolling process adjustment is an important factor leading to the uneven wall thickness of the finished pipe. The reasons for the uneven wall thickness of the spiral are as follows: due to adjustment reasons such as irregular rolling centerlines of the piercing machine, unequal inclination angles of the two rolls, or too small front pressure at the head, the wall thickness is uneven, and generally spiral along the entire length of the steel pipe. spread. During stress annealing, the small-diameter precision seamless steel pipe undergoes internal partial plastic deformation (when the stress exceeds the yield strength of the material at this temperature) or a partial relaxation process (when the stress is less than the yield strength of the material at this temperature) Relax the residual stress at a certain temperature to achieve the purpose. During the stress annealing process, the...
Duplex Stainless Steel Coil One is that duplex stainless steel with chromium content in the range of 18%-22% has excellent neutral chloride stress corrosion resistance under low stress conditions. 18-8 austenitic stainless steel, which is usually used in neutral chloride solutions above 70Y, is more prone to stress corrosion cracking, and heat exchangers made of this type of stainless steel are used in industrial media with trace amounts of chloride and hydrogen sulfide Equipment such as evaporators and evaporators are prone to stress corrosion cracking, but duplex stainless steel has good resistance. The second is that chromium-containing duplex stainless steel has good corrosion resistance. When having the same pitting equivalent value, the critical pore corrosion potential of duplex stainless steel and austenitic stainless steel is relatively similar. The pitting corrosion resistance of duplex stainless steel containing 18% chromium is equivalent to that of 316L. Duplex stainless steel containing 25% chromium, especially nitrogen-containing high-chromium duplex stainless steel, has higher pitting and crevice corrosion resistance than 316L stainless steel. The third is that it has good corrosion resistance fatigue and wear corrosion performance, and is used to make pumps, valves and other equipment under certain corrosive medium conditions. In addition, the comprehensive...
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